The present invention relates to a process of purifying gypsum using hydrocyclones. Gypsum suspensions which are purified using hydrocyclones are generated mainly in flue gas desulfurizing plants which are supplied with an aqueous suspension of a low-grade limestone.
Hydrocyclones are used in engineering methods in various ways to grade and/or thicken aqueous suspensions. Such apparatus combinations have already been described in an article by W. Grundelach and H.F.Trawinski entitled "Der Hydrozyklon" in Chemie-Ing.-Techn., 32nd Year (1960), No. 4, on pages 279 to 284. In accordance with German Patent 36 07 191, hydrocyclones are also used to remove dissolved salts and minute particles from absorption solutions of flue gas desulfurizing plants, i.e. to remove gypsum.
The previously proposed processes and apparatus combinations have the disadvantage that gypsum particles and minute inert particles are not adequately separated and the overall liquid balance is unfavorable.